A variety of organic fluoropolymers comprising a perfluoropolyether chain have unique functional characteristics such as water and oil repellency and low refractive index as well as excellent heat resistance and chemical resistance. They are thus known as polymers of great value added and finding applications in a broad range.
Meanwhile, silane compounds represented by the general formula; BSi(R).sub.3-r D.sub.r [wherein B represents an organic residue reactive to organic compounds including polymers; D represents halogen or alkoxy; R represents alkyl; r represents 1, 2 or 3] are generally known as silane coupling agents and have been used as surface-treating agents for various materials. In addition, the above moiety-terminated polymers are known to undergo hydrolysis by water at room temperature, thereby progressing condensation polymerization or crosslinking for curing [Encyclopedia of Chemical and Technology, Vol. 12, pp. 464 to 569, 1970].
Also known are attempts to modify organic fluoropolymers with such silane compounds. For example, fluorosilicone, fluoroolefin-vinylsilane copolymers, .alpha., .omega.-bis(dialkyl-chlorosilyl)polyfluoroalkanes, etc. can be mentioned as examples [Journal of Polymer Science, Part-A, Vol. 10, No. 3, pp. 947 to 953].
Japanese Kokai Publication Hei-1-294709 discloses an organic fluoropolymer containing such a vinylsilane unit. This polymer, which has both water repellency and antifouling property, is claimed to be used effectively, for example, in an automotive outside plate coating:
Japanese Kokai Publication Hei-5-339007 discloses a fluorine-containing organosilicon compound as an example of application of said silane compound to an organic fluoropolymer. This compound is characterized in that said silane compound is linked to a perfluoropolyether chain of an organic fluoropolymer and that the carbon atom to which said silane compound is bound is iodinated. This compound, which has low surface energy, is said to be of value as a material for the production of textile finishing agents, mold releasing agents, release agents or antifouling paints. PA1 Household electrical appliance parts such as fan blades, electronic range doors, refrigerator panels, etc.; office equipment parts such as copying machine contact glass, OHP body mirror, OHP sheet, keyboard, telephone receiver, desk top, etc.; home appliances and furniture such as glasses, cupboard door, looking glass, window panes, lamp shades, chandeliers, etc.; building materials such as show window, telephone box, and water tank glass members; vehicle parts such as rolling stock glass, coated surfaces of vehicle bodies, etc.; personal articles such as spectacle frames, swimming goggle glass, goggles, helmets, clockface glass, etc.; amusement equipment parts and products such as pinball machine glass panels, playing cards, mahjong tiles, etc.; coated surfaces of furniture and pianos; PA1 Personal accessories such as tie pins, necklaces, pierce-type ear-rings, etc.; metal or metal-plated members such as faucets, brasswind and woodwind instruments, golf clubs, door handles, dumbbells, cutters, etc.; ceramic products such as insulators, tiles, toilet fixtures, tableware, roofing tiles, etc.; stone products such as tombstones, go stones, marbles, etc.; paper products such as wallpaper, screen-door paper, books, posters, photographs, etc.; and leather goods such as wallets, boots and shoes, bags, wristwatch bands, baseball gloves, etc. PA1 Personal accessories such as tie pins, necklaces, pierce-type earrings, etc.; metal or metal-plated products and members such as faucets, brasswind and woodwind instruments, golf clubs, door handles, dumbbells, cutters, etc.; ceramic products such as insulators, floor tiles, toilet fixtures, tableware, roofing tiles, etc.; stone products such as tombstones, go stones, marbles, etc.; paper products such as wallpaper, screen-door paper, books, posters, photographs, etc.; leather goods such as wallets, boots and shoes, bags, wrist-watch bands, baseball gloves, etc.;
However, the silane compound-containing organic fluoropolymers so far known are not sufficiently antifouling because only one reactive silicon atom is available at the terminus of the perfluoropolyether chain. The term "antifouling" is used herein to mean both property to reject deposition of fouling matter and property to readily release a deposited fouling matter on washing.
Meanwhile, metal, glass and plastic materials are in broad use as a substrate of automotive parts, OA equipments, household electrical appliances, and among other applications. The exposed surface of those substrates tend to be contaminated by deposits of the airborne dust particles in the car interior or the office or other room, by oily substances originating from food or machine oil, or by fingerprints on handling. Therefore, those substrates must be somehow protected against such fouling and, in addition, rendered ready to wipe off fouling and other deposits.
As an antifouling technology for a glass surface, Japanese Kokai Publication Hei-1-126244 and other literatures disclose a method which comprises coating a glass surface directly with a polymer material such as polydimethylsiloxane or dipping the substrate in such a treating agent for forming a film. Another technology is also known for forming a fluorine-containing unimolecular film on a glass surface by chemisorption.
As an antifouling technology for a metal surface, Japanese Kokoku Publication Hei-7-53913 discloses a method which comprises forming a chromate layer containing a silica sol type silane coupling agent on top of a usual galvanized steel surface and then forming a thin top film using an isocyanate coating composition thereon to provide an organic composite-plated steel sheet.
However, those conventional treatments are not sufficiently effective in protecting substrates against attachment of oily contaminants. Moreover, the substrate surface, which are directly touched by hand, are liable to be contaminated by fingerprints, which cannot be easily wiped off.
Furthermore, those antifouling properties is drastically handicapped under severe conditions such as outdoor exposure so that those technologies are not fully satisfactory in terms of weatherability. In addition, the inevitable use of an expensive fluorine-containing organic solvent in a large amount is a drawback from the standpoint of production cost.
Meanwhile, the surface of substrates used in mobile equipment such as motor vehicles, rolling stock, aircraft, ships, etc., and home and other buildings are exposed to wind and rain during their use. Moreover, in districts frequented by heavy snowfalls or extremely cold climates, particularly in winter months, this surface remain directly exposed to snow and ice for a long time. Furthermore, in special establishments such as cold experiment facilities and certain household electrical appliances such as refrigerators, too, their members are partly exposed to very low temperatures so that waterdrops and moisture in the air are deposited as ice.
When ice is deposited on the surface of car substrate, its functions are adversely affected. Taking a windshield glass as an example, icing interferes with the driver's sight and may cause an accident. When ice is deposited on certain members of the refrigerator and so on, its cooling efficiency is sacrificed to increase a waste of electric energy.
Japanese Kokai Publication Hei-3-158794 discloses a technology for performing an antifogging treatment, which comprises forming a hydrophilic film.
Japanese Kokai Publication Hei-1-126244 discloses a technology for imparting water repellency to a glass surface, which comprises coating the surface directly with an organosilicone compound such as polydimethylsiloxane or dipping it in such a treating agent for forming a film.
Japanese Kokai Publication Hei-4-338147 and Japanese Kokoku Publication Sho-63-24554 disclose a technology for imparting water repellency to a glass surface, which comprises forming a fluoroalkyl-containing silicon oxide film on the surface by chemisorption or in a sol-gel process using a fluoroalkylsilane compound.
However, said antifogging treatment comprising formation of a hydrophilic film is not effective in preventing deposition of ice. In said technology which comprises forming an organosilicone compound film on a glass surface, there is much possibility that this film will be exfoliated in its use because this film is not chemically bound to glass. It is thus poor in durability. Said technology which comprises forming a fluoroalkyl-containing silicon oxide film on a glass surface insures sufficient durability but fails to provide necessary lubricity. Moreover, those technologies as used independently or in combination are not effective in preventing icing even if water repellency is secured.
For preventing icing, it is necessary in the first place to insure that icing will not occur or be hard to occur on a substrate surface in question. However, it is also important to make it easy to remove deposits of ice once formed, in view of the fact that considerable difficulties are involved in removing deposits of ice once formed. Therefore, an anti-icing agent is in demand, which is not only capable of preventing icing itself but allows deposits of ice to be removed with ease.
On the other hand, glass, which possess high optical transmission, insulation property and ornamental characteristic, have been used in a variety of applications such as residential window panes and other architectural members, vehicle members such as car and rolling stock, windshield members for ships and airplanes, among others. In those applications, glass is used in places exposed to the outdoor environment and is often exposed to rain or come in contact with seawater or contaminated water. Moreover, windshield glasses of cars and so on necessitate an important function to secure clear sight. For maintaining sufficient optical transmission, the glass itself has been required to have the property to repel rainwater or the like (this property is referred to as water repellency in this specification).
However, in said technology which comprises forming an organosilicone compound film on a glass surface, there is much possibility that this film will be exfoliated in its use because this film is not chemically bound to glass. It is thus poor in durability. Said technology which comprises forming a fluoroalkyl-containing silicon oxide film on a glass surface insures sufficient durability but fails to provide necessary lubricity and antitackiness. For instance, when the treated glass is used as the windshield of a car, the wipers will emit a beeping noise.